Commit 0b46b755 authored by Quentin Monnet's avatar Quentin Monnet Committed by Daniel Borkmann
Browse files

libbpf: Add LIBBPF_DEPRECATED_SINCE macro for scheduling API deprecations 

Introduce a macro LIBBPF_DEPRECATED_SINCE(major, minor, message) to prepare
the deprecation of two API functions. This macro marks functions as deprecated
when libbpf's version reaches the values passed as an argument.

As part of this change libbpf_version.h header is added with recorded major
(LIBBPF_MAJOR_VERSION) and minor (LIBBPF_MINOR_VERSION) libbpf version macros.
They are now part of libbpf public API and can be relied upon by user code.
libbpf_version.h is installed system-wide along other libbpf public headers.

Due to this new build-time auto-generated header, in-kernel applications
relying on libbpf (resolve_btfids, bpftool, bpf_preload) are updated to
include libbpf's output directory as part of a list of include search paths.
Better fix would be to use libbpf's make_install target to install public API
headers, but that clean up is left out as a future improvement. The build
changes were tested by building kernel (with KBUILD_OUTPUT and O= specified
explicitly), bpftool, libbpf, selftests/bpf, and resolve_btfids builds. No
problems were detected.

Note that because of the constraints of the C preprocessor we have to write
a few lines of macro magic for each version used to prepare deprecation (0.6
for now).

Also, use LIBBPF_DEPRECATED_SINCE() to schedule deprecation of
btf__get_from_id() and btf__load(), which are replaced by
btf__load_from_kernel_by_id() and btf__load_into_kernel(), respectively,
starting from future libbpf v0.6. This is part of libbpf 1.0 effort ([0]).

  [0] Closes: https://github.com/libbpf/libbpf/issues/278



Co-developed-by: default avatarQuentin Monnet <quentin@isovalent.com>
Co-developed-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Signed-off-by: default avatarQuentin Monnet <quentin@isovalent.com>
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210908213226.1871016-1-andrii@kernel.org
parent 006a5099

kernel/bpf/preload/Makefile

+5 −2
Original line number Diff line number Diff line
@@ -10,12 +10,15 @@ LIBBPF_OUT = $(abspath $(obj)) 
$(LIBBPF_A):

	$(Q)$(MAKE) -C $(LIBBPF_SRCS) O=$(LIBBPF_OUT)/ OUTPUT=$(LIBBPF_OUT)/ $(LIBBPF_OUT)/libbpf.a



userccflags += -I $(srctree)/tools/include/ -I $(srctree)/tools/include/uapi \

userccflags += -I$(LIBBPF_OUT) -I $(srctree)/tools/include/ \

	-I $(srctree)/tools/include/uapi \

	-I $(srctree)/tools/lib/ -Wno-unused-result



userprogs := bpf_preload_umd



clean-files := $(userprogs) bpf_helper_defs.h FEATURE-DUMP.libbpf staticobjs/ feature/

clean-files := $(userprogs) libbpf_version.h bpf_helper_defs.h FEATURE-DUMP.libbpf staticobjs/ feature/



$(obj)/iterators/iterators.o: $(LIBBPF_A)



bpf_preload_umd-objs := iterators/iterators.o

bpf_preload_umd-userldlibs := $(LIBBPF_A) -lelf -lz

tools/bpf/bpftool/Makefile

+4 −0
Original line number Diff line number Diff line
@@ -60,6 +60,7 @@ CFLAGS += -W -Wall -Wextra -Wno-unused-parameter -Wno-missing-field-initializers 
CFLAGS += $(filter-out -Wswitch-enum -Wnested-externs,$(EXTRA_WARNINGS))

CFLAGS += -DPACKAGE='"bpftool"' -D__EXPORTED_HEADERS__ \

	-I$(if $(OUTPUT),$(OUTPUT),.) \

	$(if $(LIBBPF_OUTPUT),-I$(LIBBPF_OUTPUT)) \

	-I$(srctree)/kernel/bpf/ \

	-I$(srctree)/tools/include \

	-I$(srctree)/tools/include/uapi \
@@ -137,7 +138,10 @@ endif 
BPFTOOL_BOOTSTRAP := $(BOOTSTRAP_OUTPUT)bpftool



BOOTSTRAP_OBJS = $(addprefix $(BOOTSTRAP_OUTPUT),main.o common.o json_writer.o gen.o btf.o xlated_dumper.o btf_dumper.o disasm.o)

$(BOOTSTRAP_OBJS): $(LIBBPF_BOOTSTRAP)



OBJS = $(patsubst %.c,$(OUTPUT)%.o,$(SRCS)) $(OUTPUT)disasm.o

$(OBJS): $(LIBBPF)



VMLINUX_BTF_PATHS ?= $(if $(O),$(O)/vmlinux)				\

		     $(if $(KBUILD_OUTPUT),$(KBUILD_OUTPUT)/vmlinux)	\

tools/bpf/resolve_btfids/Makefile

+4 −2
Original line number Diff line number Diff line
@@ -26,6 +26,7 @@ LIBBPF_SRC := $(srctree)/tools/lib/bpf/ 
SUBCMD_SRC := $(srctree)/tools/lib/subcmd/



BPFOBJ     := $(OUTPUT)/libbpf/libbpf.a

LIBBPF_OUT := $(abspath $(dir $(BPFOBJ)))/

SUBCMDOBJ  := $(OUTPUT)/libsubcmd/libsubcmd.a



BINARY     := $(OUTPUT)/resolve_btfids
@@ -41,11 +42,12 @@ $(SUBCMDOBJ): fixdep FORCE | $(OUTPUT)/libsubcmd 
	$(Q)$(MAKE) -C $(SUBCMD_SRC) OUTPUT=$(abspath $(dir $@))/ $(abspath $@)



$(BPFOBJ): $(wildcard $(LIBBPF_SRC)/*.[ch] $(LIBBPF_SRC)/Makefile) | $(OUTPUT)/libbpf

	$(Q)$(MAKE) $(submake_extras) -C $(LIBBPF_SRC)  OUTPUT=$(abspath $(dir $@))/ $(abspath $@)

	$(Q)$(MAKE) $(submake_extras) -C $(LIBBPF_SRC)  OUTPUT=$(LIBBPF_OUT) $(abspath $@)



CFLAGS := -g \

          -I$(srctree)/tools/include \

          -I$(srctree)/tools/include/uapi \

          -I$(LIBBPF_OUT) \

          -I$(LIBBPF_SRC) \

          -I$(SUBCMD_SRC)
@@ -54,7 +56,7 @@ LIBS = -lelf -lz 
export srctree OUTPUT CFLAGS Q

include $(srctree)/tools/build/Makefile.include



$(BINARY_IN): fixdep FORCE | $(OUTPUT)

$(BINARY_IN): $(BPFOBJ) fixdep FORCE | $(OUTPUT)

	$(Q)$(MAKE) $(build)=resolve_btfids



$(BINARY): $(BPFOBJ) $(SUBCMDOBJ) $(BINARY_IN)

tools/lib/bpf/Makefile

+17 −7
Original line number Diff line number Diff line
@@ -8,7 +8,8 @@ VERSION_SCRIPT := libbpf.map 
LIBBPF_VERSION := $(shell \

	grep -oE '^LIBBPF_([0-9.]+)' $(VERSION_SCRIPT) | \

	sort -rV | head -n1 | cut -d'_' -f2)

LIBBPF_MAJOR_VERSION := $(firstword $(subst ., ,$(LIBBPF_VERSION)))

LIBBPF_MAJOR_VERSION := $(word 1,$(subst ., ,$(LIBBPF_VERSION)))

LIBBPF_MINOR_VERSION := $(word 2,$(subst ., ,$(LIBBPF_VERSION)))



MAKEFLAGS += --no-print-directory
@@ -59,7 +60,8 @@ ifndef VERBOSE 
  VERBOSE = 0

endif



INCLUDES = -I. -I$(srctree)/tools/include -I$(srctree)/tools/include/uapi

INCLUDES = -I$(if $(OUTPUT),$(OUTPUT),.)				\

	   -I$(srctree)/tools/include -I$(srctree)/tools/include/uapi



export prefix libdir src obj
@@ -111,7 +113,9 @@ SHARED_OBJDIR := $(OUTPUT)sharedobjs/ 
STATIC_OBJDIR	:= $(OUTPUT)staticobjs/

BPF_IN_SHARED	:= $(SHARED_OBJDIR)libbpf-in.o

BPF_IN_STATIC	:= $(STATIC_OBJDIR)libbpf-in.o

VERSION_HDR	:= $(OUTPUT)libbpf_version.h

BPF_HELPER_DEFS	:= $(OUTPUT)bpf_helper_defs.h

BPF_GENERATED	:= $(BPF_HELPER_DEFS) $(VERSION_HDR)



LIB_TARGET	:= $(addprefix $(OUTPUT),$(LIB_TARGET))

LIB_FILE	:= $(addprefix $(OUTPUT),$(LIB_FILE))
@@ -136,7 +140,7 @@ all: fixdep 


all_cmd: $(CMD_TARGETS) check



$(BPF_IN_SHARED): force $(BPF_HELPER_DEFS)

$(BPF_IN_SHARED): force $(BPF_GENERATED)

	@(test -f ../../include/uapi/linux/bpf.h -a -f ../../../include/uapi/linux/bpf.h && ( \

	(diff -B ../../include/uapi/linux/bpf.h ../../../include/uapi/linux/bpf.h >/dev/null) || \

	echo "Warning: Kernel ABI header at 'tools/include/uapi/linux/bpf.h' differs from latest version at 'include/uapi/linux/bpf.h'" >&2 )) || true
@@ -154,13 +158,19 @@ $(BPF_IN_SHARED): force $(BPF_HELPER_DEFS) 
	echo "Warning: Kernel ABI header at 'tools/include/uapi/linux/if_xdp.h' differs from latest version at 'include/uapi/linux/if_xdp.h'" >&2 )) || true

	$(Q)$(MAKE) $(build)=libbpf OUTPUT=$(SHARED_OBJDIR) CFLAGS="$(CFLAGS) $(SHLIB_FLAGS)"



$(BPF_IN_STATIC): force $(BPF_HELPER_DEFS)

$(BPF_IN_STATIC): force $(BPF_GENERATED)

	$(Q)$(MAKE) $(build)=libbpf OUTPUT=$(STATIC_OBJDIR)



$(BPF_HELPER_DEFS): $(srctree)/tools/include/uapi/linux/bpf.h

	$(QUIET_GEN)$(srctree)/scripts/bpf_doc.py --header \

		--file $(srctree)/tools/include/uapi/linux/bpf.h > $(BPF_HELPER_DEFS)



$(VERSION_HDR): force

	$(QUIET_GEN)echo "/* This file was auto-generated. */" > $@

	@echo "" >> $@

	@echo "#define LIBBPF_MAJOR_VERSION $(LIBBPF_MAJOR_VERSION)" >> $@

	@echo "#define LIBBPF_MINOR_VERSION $(LIBBPF_MINOR_VERSION)" >> $@



$(OUTPUT)libbpf.so: $(OUTPUT)libbpf.so.$(LIBBPF_VERSION)



$(OUTPUT)libbpf.so.$(LIBBPF_VERSION): $(BPF_IN_SHARED) $(VERSION_SCRIPT)
@@ -224,10 +234,10 @@ install_lib: all_cmd 
		cp -fpR $(LIB_FILE) $(DESTDIR)$(libdir_SQ)



INSTALL_HEADERS = bpf.h libbpf.h btf.h libbpf_common.h libbpf_legacy.h xsk.h \

		  bpf_helpers.h $(BPF_HELPER_DEFS) bpf_tracing.h	     \

		  bpf_helpers.h $(BPF_GENERATED) bpf_tracing.h	     \

		  bpf_endian.h bpf_core_read.h skel_internal.h



install_headers: $(BPF_HELPER_DEFS)

install_headers: $(BPF_GENERATED)

	$(call QUIET_INSTALL, headers)					     \

		$(foreach hdr,$(INSTALL_HEADERS),			     \

			$(call do_install,$(hdr),$(prefix)/include/bpf,644);)
@@ -240,7 +250,7 @@ install: install_lib install_pkgconfig install_headers 


clean:

	$(call QUIET_CLEAN, libbpf) $(RM) -rf $(CMD_TARGETS)		     \

		*~ .*.d .*.cmd LIBBPF-CFLAGS $(BPF_HELPER_DEFS)		     \

		*~ .*.d .*.cmd LIBBPF-CFLAGS $(BPF_GENERATED)		     \

		$(SHARED_OBJDIR) $(STATIC_OBJDIR)			     \

		$(addprefix $(OUTPUT),					     \

			    *.o *.a *.so *.so.$(LIBBPF_MAJOR_VERSION) *.pc)

tools/lib/bpf/btf.h

+2 −0
Original line number Diff line number Diff line
@@ -50,9 +50,11 @@ LIBBPF_API struct btf *libbpf_find_kernel_btf(void); 


LIBBPF_API struct btf *btf__load_from_kernel_by_id(__u32 id);

LIBBPF_API struct btf *btf__load_from_kernel_by_id_split(__u32 id, struct btf *base_btf);

LIBBPF_DEPRECATED_SINCE(0, 6, "use btf__load_from_kernel_by_id instead")

LIBBPF_API int btf__get_from_id(__u32 id, struct btf **btf);



LIBBPF_API int btf__finalize_data(struct bpf_object *obj, struct btf *btf);

LIBBPF_DEPRECATED_SINCE(0, 6, "use btf__load_into_kernel instead")

LIBBPF_API int btf__load(struct btf *btf);

LIBBPF_API int btf__load_into_kernel(struct btf *btf);

LIBBPF_API __s32 btf__find_by_name(const struct btf *btf,